North Korea’s planned rocket launch is shaping up as the first major test of how China, led by Xi Jinping, will handle its impoverished neighbor sticking to costly nuclear weapons and ballistic missile programs in defiance of international pressure.

Officials in Seoul and Washington say they have been in close consultation with Beijing over ways to dissuade Pyongyang from launching its rocket and possible measures to be taken if it pushes ahead with the launch. China has shown a notably different attitude toward the recalcitrant North, according to some diplomatic sources here.

The changing atmosphere in Beijing has been reflected in a series of statements issued by the Chinese Foreign Ministry, which employed an increasingly harder rhetoric.

In a statement released a day after North Korea announced its plan to launch what it claimed to be a satellite rocket between Dec. 10-22, China acknowledged Pyongyang’s right to the peaceful use of outer space, but stressed that it was subject to restrictions imposed by the U.N. Security Council’s relevant resolutions.

On Tuesday, a Chinese Foreign Ministry spokesman hoped that North Korea would act prudently. Two days later, he stepped up the tone, saying Pyongyang ought to act prudently from the standpoint of peace and stability on the Korean Peninsula.

These remarks were in sharp contrast to the vague-worded statement Beijing issued before North Korea’s failed missile launch in April, which called for efforts to “solve the problem in a peaceful way through diplomatic channels.”

This time, China appears to feel the need to take a tougher stance against its unpredictable neighbor, which unveiled the rocket launch plan a day after Xi’s special envoy visited Pyongyang to call for its restraint.

The new Chinese leader’s practical personality as a no-nonsense man, which is demonstrated in a crackdown on an inefficient and showy bureaucracy, may signal Beijing’s departure from its unconditional siding with Pyongyang.

China remains North Korea’s only major ally and the main source of food and fuel for keeping its moribund economy ― and rigid regime ― from collapsing. Beijing, however, has been reluctant to use its leverage to tame Pyongyang’s behavior, fearing that the pressure could cause an implosion leading to political chaos and a flood of refugees across its border.

But from this same viewpoint, it seems to be in China’s best interests to discourage North Korea from firing off the rocket. Additional international sanctions that would follow the launch ― and China would find no cause to block ― would further destabilize the regime under its inexperienced young leader Kim Jong-un. It would be more burdensome for China to prop up North Korea in the wake of the rocket launch.